The present invention relates to a simultaneous drawing and false-twisting process and apparatus and, more particularly, to a drawing and false-twisting process and apparatus capable of heating yarn sufficiently in a short distance and also avoiding a substantial increase leakage external leak of steam from a heater and a reduction of mechanical strength of a product textured yarn.
Hitherto, it is known to use a dry heating device such as a heating plate as a heating means in a high-speed false twisting process. The current increasing of the processing speed, however, requires an impractical length of the heating region. It is also known to thermally set the yarn while imposing a false twisting by passing the yarn through a heating device. According to this method, it is necessary to use steam of a high temperature and pressure, particularly when the yarn is made of polyester fibers requiring a high setting temperature. The result is a difficulty in the construction of the sealing mechanism in the wet heating device.
It is also known to effect a false twisting simultaneously with a drawing by treating an undrawn or partially drawn yarn by a drawing and false-twisting apparatus. However, since the undrawn or partially drawn yarn has a large diameter, it is necessary to make the yarn passage at the yarn inlet section of the wet heat-setting device to have a sufficiently large diameter, resulting in an increased leak of the steam to the outside. In addition, since the yarn is brought into contact with steam of high temperature before sufficient orientation and crystallization, the yarn tends to be crystallized excessively causing a reduction of the strength of the textured yarn and permitting a generation of nap.